The present invention relates to a wall supporting arrangement, especially for supporting mine gallery walls. More particularly, it relates to a wall supporting arrangement including one supporting frame or a plurality of supporting frame portions.
In wall supporting arrangements for mines, tunnels, or galleries it has been known to utilize I-shaped or trough-shaped frame elements. These known integral frame elements have the disadvantage that when the depth increases and the rock pressure becomes correspondingly greater, it is difficult to distribute increased mass of material over the frame elements in the case of heavier supporting frames so as to maintain satisfactory relationship between expenditures of material or weight per meter and loading of the frame elements during their practical utilization. Heavier frame elements of correspondingly larger cross-section are also difficult to produce by rolling and cannot readily be bent with a sufficiently small radius of curvature for use as curved segments.
Since the frame elements, especially in an arched supporting arrangement are subjected not only to flexing but also to bending, tilting and torsion, especially when they are used in an arched underground passage, wherein these stresses often pass into a plastic deformation range, it is not sufficient, in contradiction to the usual condition in the construction industry, to design frame elements only or substantially with respect to possible high load-bearing capacity, that is to achieve possibly high static values; rather, it is necessary even at the cost of accepting less high static values, to select primarily the shape-retaining capability or shape stability of the frame elements so as to make the latter sufficiently resistant to the above-mentioned complex loads. The shape stability of the frame elements must be such as to withstand not only flexing loads and sharp bending loads, but also to resist tilting forces, as well as high torsional and arching forces.
It has been shown that when one-piece load frame elements are used it is difficult to optimally satisfy all of the above-mentioned requirements in dependence upon one another, inasmuch as the great rock pressure prevailing at increasing depths require utilization of heavier frame elements with correspondingly greater transverse dimensions. Inasmuch as the frame elements with due regard to sufficient shape stability must be thick-walled, even when this does not contribute to an increase of static strength, the relationship between expenditures of material and utilization of material for the carrying capacity or loading capacity of the frame elements becomes the less satisfactory, the greater and stronger the dimensions of the frame elements must be selected to withstand the increased load.